[U-Boot] When to create a SoC directory for ARM

[Sharma Bhupesh-B45370]

> -----Original Message-----
> From: u-boot-bounces at lists.denx.de [mailto:u-boot-bounces at lists.denx.de]
> On Behalf Of Scott Wood
> Sent: Friday, September 27, 2013 12:53 AM
> To: FengHua
> Cc: trini; sun york-R58495; u-boot
> Subject: Re: [U-Boot] When to create a SoC directory for ARM
> 
> On Thu, 2013-09-26 at 13:23 +0800, FengHua wrote:
> > > Date: Wed, 25 Sep 2013 20:10:13 -0500
> > > From: Scott Wood <scottwood at freescale.com>
> > > Subject: Re: [U-Boot] When to create a SoC directory for ARM
> > > To: sun york-R58495 <R58495 at freescale.com>
> > > Cc: Rini <trini at ti.com>, Wood Scott-B07421 <B07421 at freescale.com>,
> > > 	"u-boot at lists.denx.de" <u-boot at lists.denx.de>, Tom
> > > Message-ID: <1380157813.24959.237.camel at snotra.buserror.net>
> > > Content-Type: text/plain; charset="UTF-8"
> > > On Wed, 2013-09-25 at 20:04 -0500, sun york-R58495 wrote:
> > > > On Sep 25, 2013, at 4:52 PM, Scott Wood wrote:
> > > >
> > > > > On Wed, 2013-09-25 at 16:30 -0700, York Sun wrote:
> > > > >> Dear Wolfgang,
> > > > >>
> > > > >> I failed to find the guideline, here is my question. Pardon me
> > > > >> if this is a dump question as I am still new to ARM.
> > > > >>
> > > > >> As David Feng post his patch set to add ARMv8 support, I am
> > > > >> trying to enable it for Freescale implementation. Let's name it
> > > > >> as LS2 for this discussion. I am thinking to reuse as much as
> > > > >> possible for existing codes, which include copying some header
> > > > >> files from powerpc partially. I noticed the SoC field in
> > > > >> boards.cfg file and I am wondering how to use it effectively. I
> > > > >> want to put LS2 specific headers to
> > > > >> arch/arm/include/asm/arch-ls2. Do I need to copy all files from
> > > > >> arch/arm/include/asm/arch-armv8/? There aren't many but I see
> > > > >> mmu.h is included in start.S. I have been searching case like
> this in ARMv7 but didn't see shared header file (maybe I missed it).
> Please advise.
> > > > >
> > > > > LS2 is (or perhaps more accurately, contains) an implementation
> > > > > of ARMv8, so you should be using arch-armv8 rather than copying
> it.
> > > >
> > > > True. But I guess LS2 won't be the only "LS" Freescale is going to
> > > > make. Where is the best place to put the header file for chassis
> > > > related registers, like CCSR we have for mpc8xxx.
> > > Anything that isn't deeply tied to the ARM architecture should
> > > probably just go in include/.
> > > >  I am thinking the
> > > > best place is arch/arm/include/asm/ls2 (or a better name). Like
> > > > other
> > > > ARMv7 variants, I am thinking to put ls2 under arch/arm/cpu/armv8/
> > > > as well, to host LS-specific code.
> >
> > > Likewise, if it's specifically tied to armv8 it should go in
> > > arch/arm/include/asm/arch-armv8, but I'm not sure what would be tied
> > > to both armv8 and ls2.  Most likely anything LS-specific that needs
> > > to go under arch/arm/ should go somewhere like
> > > arch/arm/include/asm/ls/ (similar to arch/arm/include/asm/imx-
> common).
> >
> > > -Scott
> > all SOC specific include file should be in
> > arch/arm/include/asm/arch-SOC/ or some common directory(like
> > include/asm/imx-common). Currently, u-boot only link SOC
> > specific(arch-SOC) include directory.
> > You could touch a mmu.h file in arch/arm/include/asm/arch-ls2/ and
> > include arch/arm/include/asm/arch-armv8/mmu.h.
> > or move arch-armv8/mmu.h to arch/arm/include/asm/ to make it as a
> > generic file.
> > Maybe we should distinguish architecture specific include directory
> > and SOC  specific include directory.
> 
> Is the XXX arch-XXX supposed to be an SoC family or a CPU
> family/architectutre?
> 

Usually in 'arch/arm/include/asm' we have both:
- arch-armv7 (Arch specific. Houses stuff common to ARMv7 CPU, e.g. Global timer, SP805 WDT..)
- arch-mx6 (SoC family specific. Houses stuff like SoC specific IOMUX pads..)

We should have something similar for LayerScape.

Regards,
Bhupesh